Severe Tornadoes cause massive damage across Dallas, Fort Worth and North Texas

A powerful tornado is seen touching down near the city of Dallas, TX., April 3, 2012.

Powerful tornados were spotted on the ground in Texas, carving a path of destruction through the Dallas area and tossing tractor trailers into the air before moving north through the state.

Residents in four Texas counties are being urged to take shelter in Dallas, Ellis, Johnson and Tarrant counties.

A tornado near Dallas-Fort Worth International Airport ripped through a tractor-trailer park and tossed the massive trucks high into the air and spinning them around before smashing them to the ground.

Reports of injuries were not immediately known, but the National Weather Service declared the Dallas-Fort Worth metro area to be under a "tornado emergency." Warnings for most counties are still active.

Sirens were going off in downtown Dallas and Fort Worth. Schools across the area were huddling children in hallways. Passengers at DFW International Airport were being rushed to safe areas at 1:50 p.m. CT.

"This is as serious of a tornado we've seen in years," said CBS 11 meteorologist Larry Mowry.

Television news helicopters broadcast images of the twisters. Spotters on the ground estimated the tornadoes to be 1/2-mile wide. The first tornado, first spotted about 20 miles south of Fort Worth, was believed to be on the ground for 30 minutes.

That twister was captured on video near Arlington.

Storm spotters were reporting widespread major damage of homes and other buildings in communities south of Fort Worth.